In order to acquire evolution law of temperature field of laser remelting plasma sprayed Ni-based gradient coating on Ti6Al4V alloy surface，the effects such as heat conduction, heat radiation, heat convection ,phase change and materials highly non-linearity on coatings and substrate are taken into account comprehensively, and a 3D finite element model(FEM) of multi-tracks laser remelting temperature field is established. The analysis results show that mechanical bonding between coatings and substrate change into metallurgical bonding on present processing parameter，the depth of alloy belt vary in each scanning track and the average depth of alloy belt become deeper gradually with the increment of scanning lines. Temperature changing regular of different points on scanning tracks along scanning direction is similar. Temperature become higher and higher in succeeding scanning tracks due to the heat accumulation effect in laser remelting process. The cooling rate on the mid-points of each scanning track reaches 1200 /s above. The thermal gradient from coatings to substrate along Z direction is absolutely predominant compared with that along X,Y direction, so heat dissipates mainly along the direction normal to substrate which help to crystal grain grown preferentially.